The present invention relates to an instrument means for use in radiotherapy, and more particularly to an instrument means for inserting a plurality of parallel hollow stainless steel needles into the body for interstitial implanation of radioactive materials during the treatment of malignant tumors.
The interstitial implantation of radioactive isotopes is a well established technique for the treatment of malignant tumors. Short lengths of a radioactive source, such as Iridium-192, are linearly arranged within thin walled plastic tubes to form "ribbons." These ribbons are used as temporary interstitial implants in a wide variety of clinical situations. Each ribbon, which is very flexible, must be inserted into the body with the aid of a rigid trocar, in the form of a hollow stainless steel needle, which is sharpened at one end for piercing the skin and tumor bearing tissue. An array of the hollow needles are first inserted into the tissues to be implanted. The needles are typically spaced evenly throughout the volume of tissue to be irradiated, and are parallel to one another to avoid areas of underdose or overdose. After the hollow needles have been inserted, ribbons of radioactive sources are inserted into the bores of the needles to a position determined by the location of the tumor bearing tissue. In certain clinical situations the needles may be left in place in the body, along with the sources, for the duration of the implant, after which both are removed. In other situations, the needles may be pulled out of the body, leaving behind only the ribbon sources for the duration of the implant.
For example, when the implantation is for tumors of the head and neck area, the needles are usually inserted in an array of one or more planes, each plane comprising typically two to four parallel and equally spaced needles. In performing such an implant, the insertion of multiple parallel needles in such planes is difficult without the use of external guidance, such as provided by a template.
In the past templates consisting of rigid plates provided with a series of parallel guide holes have been applied to the body surface for inserting needles in parallel paths into the body. However these external templates are only useful on relatively flat surfaces of the body, where the entire face of the template can be readily secured and held in contact with the skin surface for stability and accuracy in guiding the needles in the desired direction. They are not suited for use on irregular or contoured body surfaces such as in the head and neck areas. Since the prior art templates are designed for placement directly on the skin surface for percutaneous implants, they are also not suitable for use when needles must be inserted directly into open body cavities to irradiate tissues adjacent to or within these cavities. Even if such templates were to be used in areas with irregular body surface contours or within body cavities, they would have to be manually retained in position, thereby preventing the use of bimanual stereotactic guidance by the radiotherapist in the insertion of the needles. It would also make the insertion of multiple needles cumbersome, especially within the body cavities where space is limited.
A needle insertion instrument means for interstitial radiotherapy which permits the simultaneous insertion in difficult areas of a plurality of spaced parallel needles in a single plane, and requires only one hand for its operation while permitting the other hand to remain free to support the area of the body being implanted for providing continuous bimanual stereotactic guidance of the needles as they are advanced into the body, would be of great advantage in allowing easier, more accurate, and faster insertion of such needles.